The invention relates to a torsional vibration damper, especially for installation in the drive line of a motor vehicle.
From German Patent No. 2,848,748 a torsional vibration damper is known having three disc parts rotatable about a common axis of rotation, of which two outer disc parts enclose a middle disc part axially between them. The two outer disc parts are formed as gaplessly closed castings which are firmly connected with one another to form a unit which is rotatable about the common axis of rotation in relation to the middle disc part and encloses the middle disc part in sealed manner. The unit of the two outer disc parts is rotationally elastically coupled with the middle disc part through several springs staggered in relation to one another in the circumferential direction, the springs being arranged in axially corresponding apertures of the three disc parts. Radially between the rotation axis and the springs each of the two outer disc parts is sealed off in relation to the middle disc part through sealing rings. Thus the two outer disc parts form a housing which as a whole is sealed off to the exterior but is rotatable in relation to the middle disc part. The housing can be filled at least partially with a lubricant in order to reduce the wear between components resting on one another or moving in relation to one another.
The constructional expense f the known torsional vibration damper is comparatively high, especially if, as usual in such torsional vibration dampers, friction devices are to be provided for damping.
It is an object of the invention to improve an enclosed torsional vibration damper of the kind as explained above which may be filled at least partially with a lubricant, so that the friction torque caused by seals has exactly predeterminable values. The torsional vibration damper should furthermore have comparatively low constructional expense and more especially the minimum friction torque which can be achieved with such a torsional vibration damper should be exactly predetermined.